|There isn't much info online in regards to removing mywebsearch from Safari browser with MAC OS.|
All is not lost however, SOPHOS offer "Sophos Anti-Virus for Mac Home Edition" which is free for home use (OS X 10.4 or later):
Better news is that SOPHOS has a mywebsearch definition in their database which should allow you to remove it.
The page linked below is for Windows OS's, but I can't see why they wouldn't include the detection for a MAC:
In any case it is worth a shot.